This invention relates to a holding device for holding one cam shaft of an engine relative to another cam shaft of an engine to prevent rotation of the cam shafts.
The holding device of the invention has been devised for restraining cam shafts of a double overhead cam shaft internal combustion engine against rotation. Where an internal combustion engine has four cam shafts, two holding devices according to the invention may be employed to prevent the cam shafts of each pair of cam shafts from rotating relative to the other cam shaft of that pair.
In internal combustion engines a toothed timing belt is trained around toothed pulleys or sprockets mounted to ends of the cam shafts. These belts require periodic replacement and to ensure that the timing relationship between the cam shafts and crank shaft of the engine is not lost, the cam shafts may need to be held against rotation relative to one another while the belt is removed and a new timing belt is fitted.
Tools for effecting such immobilization of cam shafts are available. Often such tools are specifically designed for a particular type of engine and are not usable for other engines. This requires a selection of tools to be stocked in order to enable workshops to perform replacement of timing belts for a variety of different engines types.
U.S. Pat. No. 6,332,256 discloses a holding device intended to be adjustable so that it may suit engines of a variety of types. The holding device of U.S. Pat. No. 6,332,256 is particularly complex in its construction and has a plurality of holding members arranged in pairs with at least three of the holding members being adjustable relative to one another and in one embodiment four clamps are present in order to allow the holding members to be locked relative to one another in a desired orientation.
The arrangement of U.S. Pat. No. 6,332,256, whilst being adjustable, is of a particularly complex construction and relatively difficult to operate.